- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44551 > LM27402MHX (NATIONAL SEMICONDUCTOR CORP) SWITCHING CONTROLLER, 1350 kHz SWITCHING FREQ-MAX, PDSO16 PDF資料下載
參數(shù)資料
| 型號： | LM27402MHX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 1350 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 5 X 4.40 MM, 0.90 MM HEIGHT, 0.65 MM PITCH, ETSSOP-16 |
| 文件頁數(shù)： | 15/32頁 |
| 文件大?。?/td> | 653K |
| 代理商： | LM27402MHX |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁當(dāng)前第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁
turn and input capacitor return should also be closely coupled
to minimize parasitic ground inductance. During the low-side
FET on time, current flows from ground through the low-side
FET and to the output capacitor through the inductor. It is es-
sential the input capacitor is also closely coupled with the low-
side FET source.
MOSFET Layout
With FETs acting as switches in a switching regulator, good
layout is essential. Current is constantly transitioning from the
high-side FET to the low-side FET so it is essential to place
the source of the high-side FET next to the drain of the low-
side FET and the switch-node side of the inductor. This will
minimize any parasitic inductance between the switch-node
and the FETs which can cause switch-node ringing. The FETs
can become very hot due to internal power dissipation. Using
vias to connect the drain of the FETs to other layers may help
spread the heat. The switch-node copper area should not be
so small that the low-side FET will not be able to spread its
heat.
As seen in the POWER / EFFICIENCY CALCULATIONS sec-
tion, the rise times of the FETs can significantly affect the
efficiency. Therefore, it is good layout practice to maintain the
shortest path from the LG/HG gate pins to the pins of the low-
side/high-side FETs to minimize the parasitic inductance. The
high-side gate trace should be coupled with the switch-node
trace since the internal high-side gate drive is connect be-
tween CBOOT and SW. The low-side FET gate trace should
be coupled with ground return since the internal low-side gate
driver is powered between VDD and ground. A good trace
width is around 0.015 inches to support the high transient
currents. During switching transition, it is common to see peak
transient currents of 1 - 2A flowing through gate traces so
minimizing the parasitic inductance is crucial to fast and effi-
cient switching.
Noise
Because of the high energy switching characteristic of the
switching regulator, it is good practice to separate noise gen-
erating circuitry from noise sensitive circuitry. For a buck
regulator, this means separating the switch-node from the
feedback circuitry. This can be achieved by distance or can
be shielded on the back side of the board through an internal
copper ground plane.
Reducing the noise in the DCR sense circuitry is imperative
to realize accurate effective over-current response. Separa-
tion of this circuitry from the switch-node and gate drivers will
reduce the amount of switching noise pickup at the input of
the current limit comparator. Running the DCR sense traces
in parallel as a differential pair can significantly reduce the
effect of any system noise (including switch-node pickup) at
the input of the current limit comparator.
The SW pin of the LM27402 receives signals directly from the
switch-node of the regulator to collect switching information.
This is an unimpeded noise path that may cause erratic
switching behavior if excessive noise is injected from the
switch-node. If needed, a snubber can be used to limit the dv/
dt of the signal effectively reducing the noise into the switch-
node sense pin.
Controller Layout
Proper layout practices of the controller can help guarantee
proper operation.Locating the input decoupling capacitor
(C
F), as close as possible to the VDD capacitor (CVDD) with
the LM27402 GND will help increase noise immunity.
www.national.com
22
LM27402
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2770SD-12157/NOPB | SWITCHED CAPACITOR REGULATOR, 925 kHz SWITCHING FREQ-MAX, DSO10 |
| LM2770SDX-1215/NOPB | SWITCHED CAPACITOR REGULATOR, 925 kHz SWITCHING FREQ-MAX, DSO10 |
| LM2788MM-2.0/NOPB | SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM2788MM-1.5/NOPB | SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM2788MMX-1.5/NOPB | SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM27402MHX/NOPB | 功能描述:DC/DC 開關(guān)控制器 High Perf Sync Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM27402SQ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM27402SQ/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM27402SQEVAL/NOPB | 功能描述:電源管理IC開發(fā)工具 LM27402SQ EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM27402SQX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:High Performance Synchronous Buck Controller with DCR Current Sensing |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。